The use of priors for the diagonal of the correlation matrix for EFA is particular to older EFA estimators (such as principal factoring). Mplus does not use those techniques. Instead, the default estimator is unweighted least squares, and maximum-likelihood can also be requested.

When using WLSMV estimator for an EFA is there a way to aid in determining the number of factors by 1) either examining the probability value for the Chi-Square test (non-significant) or 2) conducting a Chi-Square difference test from 2 competing number of factors?